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R.G. Ackman
wise, free fatty acids in important proportions of extracted lipids should be regarded with doubt and probably the result of enzymatic hydrolysis of original
lipids in situ. The proportions of the dominant phosphatidy1choline and of the
lesser phosphatidylethanolamine, found to be approximately 2: 1 in most tissues of
marine organisms (Vaskovsky, 1989), are also illustrated in the chromatographic
profile.
The rearrangement of the proportions of these lipid classes may be observed
under stress conditions. For example, lipid classes were studied over a whole year
with emphasis on the sexual maturation period for the freshwater crustacean
Macrobrachium borellii (Gonzalez-Baro and Pollero, 1988). The different lipids
of the muscle remained almost unaltered, but the shift of lipid, especially triacylglycerols, into the female gonadal tissue from the hepatopancreas was obvious in the Southern Hemisphere summer period of October-March. In many
invertebrates, triacylglycerols are a major part of the oocyte. The effects of sexual
maturation in the marine shrimp Penaeus kerathurus have also been followed by
Mourente and Rodriguez (1991) in considerable detail. On a dry-weight basis,
ovary total lipid doubled, and triacylglycerol content increased fourfold. Polar
lipids approximately doubled, but proportions of fatty acids among important
subclasses of polar lipids did not alter except in phosphatidylethanolamine, suggesting a simple transfer of total lipid to the oocytes. The continuing fascination
with the Antarctic Euphausia superba showed some very interesting results
(Saether et aI., 1985), as in different samples both phospholipids and triacylglycerols varied with total lipid content, a situation unlike fish, in which the
muscle phospholipids are considered stable and only the depot fat triacylglycerols
vary. Females contained twice the total lipids of males; histological examinations
of the distribution of lipid in tissues were included in this report. Their observations over a range of 1-6% lipid (wet weight), including females with roe, appear
to confirm that in such crustacea total body lipid is involved in a depot lipid
function. Similar conclusions were reached by Teshima et al. (1988) for induced
maturation by destalking in the prawn Penaeus japonicus. This group also examined the lipid classes of the hemolymph, clearly involved in the vitellogenesis
process and rich in free sterol during this stage. The tiger prawn Penaeus esculentus was the subject of experimental starvation (Chandumpai et aI., 1991) to
explore the changes in digestive gland lipids. Very little triacylglycerol (8% of
body lipid) was present in that tissue and less in the muscle; the latter tissue
preserved its relative proportions of lipid classes during molting as well as during
starvation. This inability to store much lipid could lead to difficulty in molting or
reproduction if food was not readily available.
By contrast, the freshwater amphipods Diporeia spp. (formerly including Pontoporeia hoyi) deposit an extensive proportion of triacylglycerols, as much as 84%
of total lipid. Females have more lipid than males and transfer this lipid to eggs for
brooding (Cavaletto et aI., 1996). An extensive survey of energy reserve lipids in a
saline lake over 2 years is especially interesting as it shows that lag periods of lipid
deposition were of the order of 1-2 months (Arts et aI., 1993). This may explain
R.G. Ackman
wise, free fatty acids in important proportions of extracted lipids should be regarded with doubt and probably the result of enzymatic hydrolysis of original
lipids in situ. The proportions of the dominant phosphatidy1choline and of the
lesser phosphatidylethanolamine, found to be approximately 2: 1 in most tissues of
marine organisms (Vaskovsky, 1989), are also illustrated in the chromatographic
profile.
The rearrangement of the proportions of these lipid classes may be observed
under stress conditions. For example, lipid classes were studied over a whole year
with emphasis on the sexual maturation period for the freshwater crustacean
Macrobrachium borellii (Gonzalez-Baro and Pollero, 1988). The different lipids
of the muscle remained almost unaltered, but the shift of lipid, especially triacylglycerols, into the female gonadal tissue from the hepatopancreas was obvious in the Southern Hemisphere summer period of October-March. In many
invertebrates, triacylglycerols are a major part of the oocyte. The effects of sexual
maturation in the marine shrimp Penaeus kerathurus have also been followed by
Mourente and Rodriguez (1991) in considerable detail. On a dry-weight basis,
ovary total lipid doubled, and triacylglycerol content increased fourfold. Polar
lipids approximately doubled, but proportions of fatty acids among important
subclasses of polar lipids did not alter except in phosphatidylethanolamine, suggesting a simple transfer of total lipid to the oocytes. The continuing fascination
with the Antarctic Euphausia superba showed some very interesting results
(Saether et aI., 1985), as in different samples both phospholipids and triacylglycerols varied with total lipid content, a situation unlike fish, in which the
muscle phospholipids are considered stable and only the depot fat triacylglycerols
vary. Females contained twice the total lipids of males; histological examinations
of the distribution of lipid in tissues were included in this report. Their observations over a range of 1-6% lipid (wet weight), including females with roe, appear
to confirm that in such crustacea total body lipid is involved in a depot lipid
function. Similar conclusions were reached by Teshima et al. (1988) for induced
maturation by destalking in the prawn Penaeus japonicus. This group also examined the lipid classes of the hemolymph, clearly involved in the vitellogenesis
process and rich in free sterol during this stage. The tiger prawn Penaeus esculentus was the subject of experimental starvation (Chandumpai et aI., 1991) to
explore the changes in digestive gland lipids. Very little triacylglycerol (8% of
body lipid) was present in that tissue and less in the muscle; the latter tissue
preserved its relative proportions of lipid classes during molting as well as during
starvation. This inability to store much lipid could lead to difficulty in molting or
reproduction if food was not readily available.
By contrast, the freshwater amphipods Diporeia spp. (formerly including Pontoporeia hoyi) deposit an extensive proportion of triacylglycerols, as much as 84%
of total lipid. Females have more lipid than males and transfer this lipid to eggs for
brooding (Cavaletto et aI., 1996). An extensive survey of energy reserve lipids in a
saline lake over 2 years is especially interesting as it shows that lag periods of lipid
deposition were of the order of 1-2 months (Arts et aI., 1993). This may explain